Mount Sinabung is a Pleistocene-to-Holocene stratovolcano.[10] It is located in a relatively cool area on a fertile plateau with mountains bounding the north.[11] The summit crater of the volcano has a complex, longer form due to air vents migrating on the N-S line.[10] The 2,460 meter high andesitic-todacitic volcano comes from the Sunda Arc.[10] This is created by the subduction of the Indo-Australian Plate under the Eurasian Plate.[10] The Andaman Islands are on the North-Northwest bound of the arc while the Banda Arc is on the East.[12] Sinabung has a total of four volcanic craters, one of them being active currently.[1]

On 29 August 2010 (local time), the volcano experienced a minor eruption after several days of rumbling.[13] Ash spewed into the atmosphere up to 1.5 kilometres (0.93 mi) high and lava was seen overflowing the crater.[13] The volcano had been inactive for over four centuries, with the most recent eruption occurring in 1600.[13] On 31 August 6,000 of the 30,000 villagers who had been evacuated returned to their homes.[14][15] The volcano was assigned to category “B” In Indonesia, as it had been inactive for more than 400 years (volcanoes in category “A”, must be monitored frequently).[16][17] The Indonesian Red Cross Society and the Health Ministry of Indonesia sent doctors and medicines to the region.[15] The National Disaster Management Agency provided face masks and food to assist the evacuees.[15]

On Friday 3 September, two more eruptions were noted.[18] The first happened at 4:45 am in the morning, forcing more villagers to leave their houses - some of them had just returned the day before.[18] This eruption was the most intense so far, with ash spewed up into the atmosphere about 3.0 kilometres (1.9 mi) high.[18] Some hours before the eruption a warning had been issued through the volcanology agency, and most villagers were prepared to leave quickly.[19] A second eruption occurred the same evening, around 6 pm. The eruption came with earthquakes which could be noticed out to a 25.0 kilometres (15.5 mi) distance around the volcano[20]

On Tuesday 7 September, Mount Sinabung erupted yet again, its biggest eruption yet since it had become active on 29 August 2010 and experts warned of more blasts to come.[21] Indonesia's chief vulcanologist, Surono, said "It was the biggest eruption yet and the sound was heard from 8 kilometres away. The smoke was 5,000 metres in the air".[21] Heavy rain mixed with the ash to form muddy coatings, a centimetre thick, on buildings and trees.[21] Electricity in one village was cut off, but there were no casualties.[21]

The Indonesian government was reported to have evacuated around 17,500 people from the region on and around the volcano.[22] The government issued the highest-level warning for the area, which was expected to remain in force for around a week, since scientists were unfamiliar with the characteristics of the volcano, due to it having been dormant for so long.[22] The government also set up kitchens for refugees to have access to food and handed out 7,000 masks.[23] Over 10,000 people have been internally evacuated after the eruption, Secretary of the provincial administration, Edy Sofyan told Xinhua by phone.[24] Spokesman of National Disaster Management Agency Priyadi Kardono said the eruption had not been predicted earlier like other volcanoes and that authorities must conduct a quick preparation for emergency work because Mount Sinabung’s seismic activity has been monitored intensively only since Friday after it showed an increase in activity.[25] In the wake of the eruption, the National Disaster Management Agency (Badan Nasional Penanggulangan Bencana/BNPB), supported the roughly 27,489 displaced people by providing shelters.[26] In addition, "BNPB has distributed 1,000 blankets, 1,000 sleeping mats and 500 family tents.[26] The local government has allocated 50 tonnes of rice, 14,000 tins of fish, 1 water truck, 1,000 bottles of ketchup, 240 kg of instant noodles, 500 blankets, 50 family tents, 200 sleeping mats, oxygen bottles/tubes for emergency, and 5,000 packs of vitamin C and B6." [26]

The towns nearest to the volcano are Kabanjahe and Berastagi.[18] There were no disruptions reported to air services at the regional airport, Medan's Polonia.[27] One person was reported dead due to the eruption; he had respiratory problems while fleeing his home.[18]

On Sunday 15 September 2013, the volcano erupted at around 3 a.m local time.[28] More than 3,700 people were evacuated from areas within a 3 kilometre (2 mile) radius of the volcano, and five halls normally used for traditional cultural ceremonies were converted into shelters with at least 1,500 being temporarily housed.[28]

The volcano erupted again on 5 November 2013, for the third time in as many months, forcing thousands of villagers to evacuate.[29] The Indonesian Center for Volcanology and Geological Hazard Mitigation advised villagers to keep a distance of at least 2 miles from the volcano, while 5,000 people were evacuated from North Sumatra's Karo Regency.[29] The eruption has affected the people living around the volcano in more than one way; crops died due to the ash fall leading to an economic change in the area.[29] Sinabung is one of nearly 130 active volcanoes in the world's fourth-most populated country, which straddles the "Pacific Ring of Fire".[29] On 11 November 2013, a pyroclastic flow, a fast-moving avalanche of ash, lava fragments and air, was seen racing down the peak.[29] Since the eruption, Mount Sinabung has been very active in terms of having explosions of ash up to 2 times a day.[29]

On 4 January 2014, the volcano erupted again.[31] "Mount Sinabung, which has erupted over a hundred times between Jan. 4 through the morning of January 5 is spewing out a 4,000 metre (13,000 ft) high column of ash damaging property and crops and poisoning animals over a wide radius."[31]

On 1February 2014 a further eruption occurred that sent clouds of hot ash 2 kilometres (1.2 mi) into the air and engulfed nearby villages.[32] Reports claim that at least 16[33] people died as a result of the eruption, which occurred just after residents living more than five kilometers from the mountain had been allowed to return home following a lack of recent volcanic activity.[32] Among the dead were a local television journalist and four high-school students along with their teacher, who were visiting the mountain to see the eruptions up close.[34] Seven of the victims were members of the Indonesian Christian Student Movement (GMKI), who died while trying to save local residents as pyroclastic flows swept across Mount Sinabung.[35]

Eruptions continue in October 2014 from Mount Sinabung.[36] On 5 October, four eruptions in the early hours of the morning were reported by the Badan Nasional Penanggulangan Bencana (BNPB). The first eruption produced an ash plume of up to 2 km in height and a pyroclastic flow of 4.5 km in a southerly direction.

The Darwin Volcanic Ash Advisory Centre (VAAC) reported eruptions between 6 and 10 October, with some evacuations from surrounding villages.[37] Further eruptions between 20 and 25 October have resulted in a meteorological cloud of ash obscuring some satellite observation. On 26 October the pyroclastic flow travelled 3.5 km and resulted in avalanches in the area.

Recent activity on Mount Sinabung has resulted in higher levels of tourism and sight-seeing in the area.[38] The Tourism Agency of the Karo regency has officially proposed several locations to local government as potential tourist sites. Tours to different villages and viewing sites are already available in the area.

An ecosystem responds to volcanism in many different ways depending on the frequency, scale, and severity of the eruptions.[39] Furthermore, it can be assumed that the pyroclastic flow of the eruption that was an estimated 700 degrees in temperature killed many of the organic matter including plants and animals.[40] As seen in the Mount St. Helens eruption, many insects would likely die due to the ash fall. This abrasion due to the ash causes quick desiccation.[39] Although many insects may have survived from being in trees that were not torn down or deep in the ground, these insects may not live long after the event due to lack of resources.[39] Many larger animals may not have been able to escape the flow in time.[39] However, like at Mt. St. Helens, many of these animals could recover from pools of survivors and from invasion of other species.[39]